1. Field of the Invention
The present invention relates to a head-end device for a television signal distribution system serving a plurality of user installations, intended to feed at least two downgoing cables and comprising:
a set of various separate sources of television signals transmitted by satellite, called satellite sources, each of the downgoing cables being fed with different signals coming from satellite sources,
a source of television signals transmitted by terrestrial channel, called terrestrial source, and
couplers, called terrestrial signal couplers, for repeating the signals from the terrestrial source on each of the downgoing cables by adding them to the signals of a satellite source.
The invention also relates to a user connection device intended to supply signals to a user installation from a television signal distribution device according to the invention, having selection means for selecting one of the downgoing cables and connecting the installation thereto.
Such a distribution system, which finds an application in, for example, a residential building comprising a plurality of apartments is customarily called xe2x80x9cMATVxe2x80x9d.
2. Description of the Related Art
A distribution system, comprising a head-end device and user connection devices as defined in the opening paragraph above, is known from patent application EP-A-0 583 843. According to this document, various cables divide up all the available satellite channels among them and the terrestrial cables are copied on all the cables, so that one is always in a position to watch a program transmitted by a terrestrial channel, whatever the cable chosen.
Digital data channels which can be used in computers are broadcast by certain satellites. If, in the same house one user wishes to watch a television broadcast coming from a certain satellite, that is to say, carried by a certain cable, whereas another user would like to work on a computer with the data transmitted by another satellite, that is to say, carried by another cable, there is a conflict. The invention notably has for its object to remedy this conflict.
For this purpose, a device according to the invention comprises at least a down-converter for selecting from a satellite source a signal that transports digital data so as to lower the signal frequency and bring the frequency to within the frequency range of the signals transmitted by the terrestrial source, and at least a coupler, called digital signal coupler, for inserting the signal that has a lowered frequency between those coming from the terrestrial source.
Thus, since the signals from the terrestrial source are copied on each of the downgoing cables, the data signals which are added thereto are also available on all the cables.
In an advantageous embodiment, the digital signal coupler is arranged upstream of the terrestrial signal couplers on a connection coming from the terrestrial source.
Thus, only one coupler is sufficient.
A user connection device includes at least an up-converter for increasing the frequency of the lower-frequency signals which transport digital data and for bringing their frequency to within the frequency range of the signals transmitted by satellite.
Thus it is possible to use a computer that has a standard modem provided for satellite links.
In an advantageous embodiment, the user connection device moreover includes a distributor for supplying signals coming from the selected cable to at least two separate user installations.
Thus, two users may simultaneously utilize each a different broadcast.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.